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authordjm@openbsd.org <djm@openbsd.org>2018-12-07 03:39:40 +0000
committerDamien Miller <djm@mindrot.org>2018-12-27 14:30:17 +1100
commita6a0788cbbe8dfce2819ee43b09c80725742e21c (patch)
treec50cc8baa68f52a4539f90916a866fb70cb9a345
parent63bba57a32c5bb6158d57cf4c47022daf89c14a0 (diff)
upstream: only consider the ext-info-c extension during the initial
KEX. It shouldn't be sent in subsequent ones, but if it is present we should ignore it. This prevents sshd from sending a SSH_MSG_EXT_INFO for REKEX for buggy these clients. Reported by Jakub Jelen via bz2929; ok dtucker@ OpenBSD-Commit-ID: 91564118547f7807030ec537480303e2371902f9
-rw-r--r--kex.c6
-rw-r--r--kex.h3
2 files changed, 6 insertions, 3 deletions
diff --git a/kex.c b/kex.c
index 25f9f66f6..3823a9544 100644
--- a/kex.c
+++ b/kex.c
@@ -1,4 +1,4 @@
1/* $OpenBSD: kex.c,v 1.141 2018/07/09 13:37:10 sf Exp $ */ 1/* $OpenBSD: kex.c,v 1.142 2018/12/07 03:39:40 djm Exp $ */
2/* 2/*
3 * Copyright (c) 2000, 2001 Markus Friedl. All rights reserved. 3 * Copyright (c) 2000, 2001 Markus Friedl. All rights reserved.
4 * 4 *
@@ -487,6 +487,7 @@ kex_input_newkeys(int type, u_int32_t seq, struct ssh *ssh)
487 if ((r = ssh_set_newkeys(ssh, MODE_IN)) != 0) 487 if ((r = ssh_set_newkeys(ssh, MODE_IN)) != 0)
488 return r; 488 return r;
489 kex->done = 1; 489 kex->done = 1;
490 kex->flags &= ~KEX_INITIAL;
490 sshbuf_reset(kex->peer); 491 sshbuf_reset(kex->peer);
491 /* sshbuf_reset(kex->my); */ 492 /* sshbuf_reset(kex->my); */
492 kex->flags &= ~KEX_INIT_SENT; 493 kex->flags &= ~KEX_INIT_SENT;
@@ -594,6 +595,7 @@ kex_new(struct ssh *ssh, char *proposal[PROPOSAL_MAX], struct kex **kexp)
594 if ((r = kex_prop2buf(kex->my, proposal)) != 0) 595 if ((r = kex_prop2buf(kex->my, proposal)) != 0)
595 goto out; 596 goto out;
596 kex->done = 0; 597 kex->done = 0;
598 kex->flags = KEX_INITIAL;
597 kex_reset_dispatch(ssh); 599 kex_reset_dispatch(ssh);
598 ssh_dispatch_set(ssh, SSH2_MSG_KEXINIT, &kex_input_kexinit); 600 ssh_dispatch_set(ssh, SSH2_MSG_KEXINIT, &kex_input_kexinit);
599 r = 0; 601 r = 0;
@@ -839,7 +841,7 @@ kex_choose_conf(struct ssh *ssh)
839 } 841 }
840 842
841 /* Check whether client supports ext_info_c */ 843 /* Check whether client supports ext_info_c */
842 if (kex->server) { 844 if (kex->server && (kex->flags & KEX_INITIAL)) {
843 char *ext; 845 char *ext;
844 846
845 ext = match_list("ext-info-c", peer[PROPOSAL_KEX_ALGS], NULL); 847 ext = match_list("ext-info-c", peer[PROPOSAL_KEX_ALGS], NULL);
diff --git a/kex.h b/kex.h
index 593de1208..0f67f58db 100644
--- a/kex.h
+++ b/kex.h
@@ -1,4 +1,4 @@
1/* $OpenBSD: kex.h,v 1.91 2018/07/11 18:53:29 markus Exp $ */ 1/* $OpenBSD: kex.h,v 1.92 2018/12/07 03:39:40 djm Exp $ */
2 2
3/* 3/*
4 * Copyright (c) 2000, 2001 Markus Friedl. All rights reserved. 4 * Copyright (c) 2000, 2001 Markus Friedl. All rights reserved.
@@ -104,6 +104,7 @@ enum kex_exchange {
104}; 104};
105 105
106#define KEX_INIT_SENT 0x0001 106#define KEX_INIT_SENT 0x0001
107#define KEX_INITIAL 0x0002
107 108
108struct sshenc { 109struct sshenc {
109 char *name; 110 char *name;